Space-time coded MIMO-OFDM systems for wireless communications: Signal detection and channel estimation

Master'sMASTER OF ENGINEERIN

Méthodes de codage et d'estimation adaptative appliquées aux communications sans fil

Les recherches et les contributions présentées portent sur des techniques de traitement du signal appliquées aux communications sans fil. Elles s’articulent autour des points suivants : (1) l’estimation adaptative de canaux de communication dans différents contextes applicatifs, (2) la correction de bruit impulsionnel et la réduction du niveau de PAPR (Peak to Average Power Ratio) dans un système multi-porteuse, (3) l’optimisation de schémas de transmission pour la diffusion sur des canaux gaussiens avec/sans contrainte de sécurité, (4) l’analyse, l’interprétation et l’amélioration des algorithmes de décodage itératif par le biais de l’optimisation, de la théorie des jeux et des outils statistiques. L’accent est plus particulièrement mis sur le dernier thème

Mitigation of impulsive noise for SISO and MIMO G.fast system

To address the demand for high bandwidth data transmission over telephone transmission lines, International Telecommunication Union (ITU) has recently completed the fourth generation broadband (4GBB) copper access network technology, known as G.fast. Throughout this thesis, extensively investigates the wired broadband G.fast coding system and the novel impulsive noise reduction technique has been proposed to improve the performance of wired communications network in three different scenarios: single-line Discrete Multiple Tone (DMT)- G.fast system; a multiple input multiple-output (MIMO) DMTG.fast system, and MIMO G.fast system with different crosstalk cancellation methods. For each of these scenarios, however, Impulsive Noise (IN) is considered as the main limiting factor of performance system. In order to improve the performance of such systems, which use higher order QAM constellation such as G.fast system, this thesis examines the performance of DMT G.fast system over copper channel for six different higher signal constellations of M = 32, 128, 512, 2048, 8192 and 32768 in presence of IN modelled as the Middleton Class A (MCA) noise source. In contrast to existing work, this thesis presents and derives a novel equation of Optimal Threshold (OT) to improve the IN frequency domain mitigation methods applied to the G.fast standard over copper channel with higher QAM signal constellations. The second scenario, Multi-Line Copper Wire (MLCW) G.fast is adopted utilizing the proposed MLCW Chen model and is compared to a single line G-fast system by a comparative analysis in terms of Bit-Error-Rate(BER) performance of implementation of MLCW-DMT G.fast system. The third scenario, linear and non-linear crosstalk crosstalk interference cancellation methods are applied to MLCW G.fas and compared by a comparative analysis in terms of BER performance and the complexity of implementation.University of Technology for choosing me for their PhD scholarship and The Higher Committee For Education Development in Iraq(HCED

NOVEL OFDM SYSTEM BASED ON DUAL-TREE COMPLEX WAVELET TRANSFORM

The demand for higher and higher capacity in wireless networks, such as cellular, mobile and local area network etc, is driving the development of new signaling techniques with improved spectral and power efficiencies. At all stages of a transceiver, from the bandwidth efficiency of the modulation schemes through highly nonlinear power amplifier of the transmitters to the channel sharing between different users, the problems relating to power usage and spectrum are aplenty. In the coming future, orthogonal frequency division multiplexing (OFDM) technology promises to be a ready solution to achieving the high data capacity and better spectral efficiency in wireless communication systems by virtue of its well-known and desirable characteristics. Towards these ends, this dissertation investigates a novel OFDM system based on dual-tree complex wavelet transform (D

Powerline Kommunikation: Wesentliche Technologien um PLC in CE-Geräte zu integrieren

In-house PLT (Powerline Telecommunication) enables new and highly convenient networking functions without the need for additional cables on mains-powered devices. Since wireless networks are not able to reach sufficient throughput between different rooms or even floors, PLC is considered to be the ideal backbone home network medium, providing complementary and seamless interaction with wireless networks. The need to communicate information is not new. The historical overview of this thesis compares the development of PLT to radio broadcast technologies. The consumer expects technologies to operate without interferences. Today, there are coexistence problems between these two technologies. Why does this happens, and how the problems can be resolved are the main issues of this thesis. Initial calculations of the channel capacity provide encouraging results for using the mains cabling as a communication medium. Chapter 3 forecasts how PLT modems could develop in the future. The usage of frequencies above 30 MHz will increase the throughput rate. Next, the utilization of the 3rd wire (the protective earth) for communication enhances the coverage and the reliability of powerline transmissions. The reception of common mode signals and the usage of MIMO technologies enable 8 transmission paths between one pair of outlets, which improves the performance of the bad, strongly attenuated channels. Today, the main challenge for the mass deployment of PLT is the lack of harmonized international standards on interoperability and electromagnetic interference. The absence of a standard results in the undesirable situation of PLT modems interfering with technologies from different vendors and also with radio applications. Solutions for solving these problems are given in chapter 4 and chapter 5. The approach of ‘Smart Notching’ - monitoring the existence of receivable radio broadcast stations at the time and location where a PLT modem is operating, received wide resonance in the PLT and radio broadcast communities. ‘Smart Notching’, also called ‘Dynamic Notching’ or ‘Adaptive Notching’ is considered to be the key factor in solving the endless discussions about the interferences to HF radio broadcast. Details on the creation of ETSI TS 102 578 and the implementation of a demonstrator system is documented in chapter 5. Field tests conducted together with the EBU verified the efficiency of the concept. The jointly executed tests by representatives from the radio broadcast and the PLT communities became a historical event which brought the two technologies, radio receivers and PLT modems, back into one house. Finally, a vision of the future coordination of EMC and conclusions are presented.Heutige Modems zur Powerline Telekommunikation (PLT) können im Betrieb den Empfang von Kurzwellen-Rundfunk beeinträchtigen, wenn Modem und Rundfunk-Empfänger in unmittelbarer Nachbarschaft betrieben werden. Eine neue Generation von PLT Modems, in denen das Konzept von 'Smart Notching' - dem intelligenten Einfügen von Lücken in das Kommunikationsspektrum - implementiert ist, zeigt keine Interferenzen mit dem Empfang von Rundfunkdiensten. Das Rauschen auf der Niederspannungsinstallation enthält neben sonstigen Signalen - durch andere Geräte hervorgerufen - aufgrund der Antennenwirkung Information über Rundfunksender. Beim ‚Smart Notching’ erkennen PLT Modems am Betriebsort die Existenz von Rundfunksignalen, indem sie das Signalspektrum auf der Netzleitung messen. Die Echtzeit- Bewertung der aktuellen Situation am Betriebsort ermöglicht eine Adaption des PLT Systems. Damit wird die Elektromagnetische Verträglichkeit nicht a priori (zum Herstellungs-Zeitpunkt) durch Schirmung oder eine globale Reduktion des Sendepegels, sondern durch Design des Verfahrens (welches während des Betriebs angewendet wird) hergestellt. Diese Doktorarbeit beschreibt nach einem kurzen Überblick zur Historie des Rundfunks und der Datenübertragung über das Energieverteilnetz Messungen zur Ermittlung der theoretischen Kanalkapazität. Anschließend wird ein Ausblick gegeben, wohin sich zukünftige PLT Modems entwickeln werden. Dies sind vor allem der Frequenzbereich oberhalb von 30 MHz sowie die Nutzung der dritten Kupferader in den Netzleitungen: der Schutzerde. Die Verwendung von MIMO-Algorithmen (aus der kabellosen Funkübertragung (z.B. WiFi) bereits bekannt) verbessert vor allem die Wahrscheinlichkeit, eine hohe Datenrate im Gebäude sicher zu verteilen. Sorge bereitet bei PLT ebenfalls die Koexistenz mit weiteren PLT-Systemen, sowie zu xDSL. Hierfür wird ein Vorschlag gemacht, um die Interferenzen zu nicht kompatiblen PLToder DSL-Systemen zu vermeiden, ohne dass die Systeme sich gegenseitig gezielt Informationen zusenden. Das bereits oben erwähnte Konzept des ‚Smart Notching’ wird detailliert erläutert und die Implementierung eines Demonstrators auf FPGA-Basis dokumentiert. Abschließend wird noch beschrieben, wie ‚Smart Notching’ gemeinsam mit der EBU getestet wurde und wie es seinen Weg in die Welt der Standardisierung gefunden hat. Der Veröffentlichung des Standards ETSI TS 102 578 wurde im Juli 2008 einstimmig von ETSI PLT zugestimmt